The present invention relates to an absorption spectrum determining method which is capable of correctly obtaining the absorption spectrum waveform of an object by applying light from a surface of the object to inside of the object and receiving light which has diffused and reflected as passing through inside of the object at least at one point on the surface of the object and a spectrometric measuring apparatus for a light-diffusive object using the method.
Conventionally in carrying out a quantitative analysis for an object according to an absorptiometric method, when the object to be measured is fluid or gas, the transmissivity of light has been able to be measured because light passes through the object. However, when measuring an opaque object, light does not sufficiently pass through the object, therefore, the object to be measured has been preliminarily sliced or shattered to pieces before being subject to measurement of The absorption spectrum thereof.
However, the above-mentioned method cannot De adopted for measuring a living body alive. In view of the above, there is disclosed the method of applying light onto a surface of an object and receiving reflected light at another point on the same surface of the object to carry out certain calculations based on data of received light for consequently measuring information inside the object (for example, refer to the official bulletin of Japanese Patent Publication No. 11614/1986(B).
According to the above-mentioned method, light is conducted to a measurement point of a living body by means of a light emitting device to collect light which has diffused or reflected as passing through the living body, therefore, a continuous measurement can be carried out with the internal organs located at their proper positions inside the living body without inserting any part of the measuring device nor injuring the living body.
However, usually the object to be measured is not a transparent body but so-called a light-diffusive object which reflects or diffuses light in FIG. 9. In a light-diffusive object, reflection and refraction of light repeal many times in the light-diffusive object even when the distance between the light applying point A and the light receiving point B is fixed.
For the above reasons, when carrying out measurement with light application onto the surface of a light-diffusive object of the above-mentioned kind, a phenomenon of broadened absorption spectrum waveform results due to the distribution of substantial optical path length. FIG. 10 shows a graph of the above-mentioned phenomenon where the peak of the absorption spectrum waveform b measured from a surface of the object is weakened as compared with the inherent spectrum waveform a obtained through measurement by slicing the object.
The above fact has also resulted in the problem that, if carrying out an analysis of the components of the object using the measured light transmission data based on a weakened absorption spectrum waveform of the above kind, correct data has not been obtained.
Accordingly, it is an object of the present invention to provide an absorption spectrum correcting method and a spectrometric measuring apparatus using the method for measuring a light-diffusive object, the method and apparatus being capable of obtaining data of a curve similar to the inherent absorption spectrum waveform of the object by correcting an absorption spectrum waveform measured without shattering or processing the light-diffusive object when measuring the internal information the object by applying light to a light applying point on a surface of the object and receiving light which has passed through inside of the object at a light receiving point of the object to carry out an absorption spectrum analysis based on data of received light.